Microsoft Azure Blob Storage - Managing Blobs and storage containers from C#

This is the part two of Microsoft Azure Blob Storage where we will look into managing Microsoft Azure Blobs from C# and .NET.

For this blog, we are going to keep this pretty simple. We will create a new .net console application and add two Nugget packages that make it super easy to work with Microsoft Azure Blobs. Include these two Nugget Packages:

1. WindowsAzure.Storage
2. Microsoft.WindowsAzure.ConfigurationManager

Obtain Access keys from Azure Portal 

Add it Access Key to App.Config

Include Microsoft Azure Storage namespaces

using Microsoft.Azure;
using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Blob;

Add a Container in Azure Blob Storage from C#


var storageAccount = CloudStorageAccount.Parse(
                CloudConfigurationManager.GetSetting("AzureStorageConnection"));
var blobClient = storageAccount.CreateCloudBlobClient();
var container = blobClient.GetContainerReference("mycontainer");
container.CreateIfNotExists(BlobContainerPublicAccessType.Blob);


The code above obtains storage account by its key, create a connection, obtains a reference for container name mycontainer and finally create the container if it does not already exits.

Upload Image as Block Blob in Azure Storage Container

var storageAccount = CloudStorageAccount.Parse(
                CloudConfigurationManager.GetSetting("AzureStorageConnection"));
var blobClient = storageAccount.CreateCloudBlobClient();
var container = blobClient.GetContainerReference("mycontainer");
container.CreateIfNotExists(BlobContainerPublicAccessType.Blob);

var blockBlob = container.GetBlockBlobReference("imran-images/new/Imran-Duplicate.png");
using (var fileStream = System.IO.File.Open("C:\\Users\\imran\\Downloads\\imran-original.png", System.IO.FileMode.Open))
{
       blockBlob.UploadFromStream(fileStream);

}

The above code gets a reference of block blob with the name Imran-Duplicate.png under imran-images/new folder hierarchy (which does not currently exists and we are going to upload it). Then we open a file steam to an image in our local PC and pass it to Azure api for uploading to the container.

Download Block Blob from Azure Blob Storage Container

var storageAccount = CloudStorageAccount.Parse(
                CloudConfigurationManager.GetSetting("AzureStorageConnection"));
var blobClient = storageAccount.CreateCloudBlobClient();
var container = blobClient.GetContainerReference("mycontainer");
container.CreateIfNotExists(BlobContainerPublicAccessType.Blob);

var blockBlobDownload = container.GetBlockBlobReference("imran-images/Imran-Duplicate.png");
using (var fileStream = System.IO.File.Create("C:\\Users\\imran\\Downloads\\imran-downloaded-image-new.png"))
{
    blockBlobDownload.DownloadToStream(fileStream);
}

The above code download the same uploaded image in the same folder hierarchy from Microsoft Azure Storage Container to local PC.

Listing all Block Blob in a Container 

var storageAccount = CloudStorageAccount.Parse(
                CloudConfigurationManager.GetSetting("AzureStorageConnection"));
var blobClient = storageAccount.CreateCloudBlobClient();
var container = blobClient.GetContainerReference("mycontainer");
container.CreateIfNotExists(BlobContainerPublicAccessType.Blob);

foreach (var blob in container.ListBlobs())
{
         Console.WriteLine(blob.Uri);
}

The above code calls ListBlobs()  method of container instance to list URI of each blobs in the container.


Adding and updating Azure Container Metadata 

var storageAccount = CloudStorageAccount.Parse(
                CloudConfigurationManager.GetSetting("AzureStorageConnection"));
var blobClient = storageAccount.CreateCloudBlobClient();
var container = blobClient.GetContainerReference("mycontainer");
container.CreateIfNotExists(BlobContainerPublicAccessType.Blob);


container.Metadata.Clear(); // clears metadata
// adds a new metadata key-value pair associated with the container
container.Metadata.Add("UserId", "1111");

// adds a new metadata key-value pair associated with the container
container.Metadata.Add("CreatedAt", DateTime.UtcNow.ToString());

 // updates existing metadata key-value pair associated with the container
container.Metadata["UpdatedAt"] = DateTime.UtcNow.ToString();

// Finally save Metadata
container.SetMetadata();

The above code first clears all metadata associated to the contianer, then it adds a new key-value pair of CreateAt key, then it shows updating existing key-value pair by accessing dictionary by its key, finally the call to SetMetadata() updates metadata

List of Metadata associated with a container

var storageAccount = CloudStorageAccount.Parse(
                CloudConfigurationManager.GetSetting("AzureStorageConnection"));
var blobClient = storageAccount.CreateCloudBlobClient();
var container = blobClient.GetContainerReference("mycontainer");
container.CreateIfNotExists(BlobContainerPublicAccessType.Blob);

 // loads container metadata
container.FetchAttributes();
// prints all metadata associated with the container
foreach (var item in container.Metadata)
 {
       Console.WriteLine($"{item.Key} : {item.Value}");
 }

The code in section above prints out all metadata key-value pairs associated to a container.

Copy Block Blob

// Copy Block Blob
var originalImg = container.GetBlobReference("Imran.png");
var copyImg = container.GetBlobReference("Imran-copy.png");
copyImg.BeginStartCopy(originalImg.Uri, (obj) => Console.WriteLine("I am in love"), null);

Above code shows copy blobs from one container to another (a very common use case).

That's it, we have seen how we can create and manage Microsoft Azure Containers as well as Blobs.